1. Field of the Invention
The present invention relates to an apparatus used to collect human blood samples, and more particularly, relates to a blood collecting apparatus of the so-called pricking type which comprises a lancet and an end cap cooperating with the lancet.
2. Description of Prior Art
The number of diabetics is increasing worldwide, and the governmental or other organizations of many countries are making best efforts to establish a system f or earlier detection of diabetes. In general, the blood sugar test is necessary for the early detection. Owing to the recent rapid progress in electronics, the blood testing apparatuses and reagents for use to obtain the data relating to diabetes and other diseases have been made more compact, simpler and cheaper. Thus, the blood sugar test can now be conducted by people even in their houses, if so wanted. Since it is very difficult for a person to take his or her own blood sample for that test from his or her earlobe, the blood sample is usually taken from a fingertip.
"Finger-pricking devices" are widely used in hospitals and houses in order to take blood samples. Each of such devices comprises a throw-away lancet having a pointed needle end designed to pierce the fingertip (or other body portion, but the piercing of fingertip being the most cases). There have been proposed many types of such devices with the lancets.
The lancets of this kind made by, for example, Bayer A. G. (Germany), Miles Incorporated (U.S.A.) and Life Scan Corp. (U.S.A.), are commercially available. FIG. 9 of the accompanying drawings schematically shows a prior art lancet 1 incorporated in the finger-pricking device, and FIG. 10 also illustrates in outline the finger-pricking device 11.
The operation when the device or lancet is used will now be described referring to FIGS. 9 and 10.
The lancet 1 shown in FIG. 9 comprises a lancet body 5 and needle protector 7, wherein the lancet body has a pointed needle end 3 projecting to pierce the fingertip, while the protector being a guard covering the needle so as isolate it from the outside. The lancet body 5 is a one-piece molded plastics member integral with the protector 7. The projecting needle end 3 is received in and shielded by the plastics material forming the protector.
The lancet body 5 may be wrung relative to the protector 7 so that the former is separated from the latter (in the so-called "twisting-off" manner). An end 9 of the thus separated lancet body 5 will then be secured to a lancet holder 13 formed in a lancet ejector 21 of the finger-pricking device 11. This ejector 21 is linked to a spring means (not shown) which comprises a spring lockable in its compressed state by an appropriate mechanism. After setting the lancet body 5 on the finger-pricking device, an end cap 16 will be fitted thereon so that its end deck 19 can be pressed to fingertip 17.
Then the locked spring will be released to take its uncompressed position, thus springing out the lancet body 5 towards the end deck of the end cap 15 (as indicated by the arrow in FIG. 10). The fingertip 17 is pierced in this way. In detail, the pointed needle end 3 forms a small cut in the fingertip. A little amount of blood oozing from the little cut will be collected for various tests. FIG. 10 shows an instantaneous state of the pointed needle end 3 piercing the fingertip 17. Subsequent to this instant, the lancet body 15 whose needle end 3 has pricked the fingertip will automatically be retracted a little distance towards its home position, and will take a position where said needle end 3 is spaced apart from the cut surface of the fingertip.
In the described manner of collecting the blood sample by means of the lancet of the finger-pricking device, the lancet body 5 is replaced with a new one after every operation. However, the end cap 15 of the finger-pricking device remains unreplaced. The end cap, particularly its end deck 19 which has contacted the skin of fingertip as shown in FIG. 10 can hardly be removed therefrom without being stained with the blood oozing from the tested person. In a case wherein a through-hole formed through the end deck for passing the needle is small and tight, the possibility of the contamination of end deck will be much higher.
There may be another case wherein one and the same finger-pricking device is used in common by some persons. One of them may be apt to use it only by replacing the lancet body but without sterilizing the end deck 19 of the end cap. In such an event, the small cut in his or her fingertip is very likely to come into contact with the blood of the other persons who have used that device to take their blood samples. If said other persons were carriers of AIDS virus or B-virus of hepatitis, the one person who thereafter uses the same device would possibly be infected with the virus of said disease. Thus, the finger-pricking device must be used with the greatest possible care. Further, there is another problem that the sticking or residual blood of a person who used the device before another person would occasionally be mixed with the newly taken blood sample to thereby disable accurate blood tests.
The end cap of the finger-pricking device may be renewed every time when a blood sample is taken, in order to avoid such an infection or contamination. According to a proposal which was made, the lancet is built in each end cap when it is manufactured. This end cap with its internal lancet will be replaced with a new one whenever used for sampling of blood. An example of blood sampling devices of this type is disclosed on the Patent Laying-Open Gazette Hei. 3-30757 and are put in the market by Miles Corporation (U.S.A.). This proposed device is however somewhat complicated and sophisticated in its structure so that its higher price would cause an additional expense to users.
The finger-pricking device shown in FIG. 10 will bring about a still further problem when it is used. After used to take a blood sample, the end cap 15 has to be removed to expose the lancet body 5 in order to manually detach it from the lancet holder 13. The needle end 3 thus exposed will possibly pierce the skin of an operator removing the lancet body 5, or come into contact with his or her wound. The blood which has oozed out of a patient and is sticking to the needle end will cause the aforementioned virus infection between the operator and the patient, if they are not the same person (as is the case in the tests carried out within a hospital).
It is a still another problem that, when the bloodstained lancets are discarded as they are, the needle ends may cause a danger of injuring those who handle same, also resulting in the infection of virus.